Writing tool



April 15, 196 9 H. K. A." sos WRITING 'IOO L Sheet Filed Nov. 17, 1967!FIG. 7

H. K. A. BROSS April 15, 1969 WRITING TOOL Sheet "2 6r 2 Filed Nov. 1'7,1967 FIG."

- FIG.1 2

FIG.16

FIG. 15

FIG.19 FIG.17 FIG. 18

FIG. 14

INVENTOR! 5 M 5 m 8 W n M O fv m%% A [Y MB K T- a I e H United StatesPatent 3,438,715 WRITING TOOL Helmut Karl Anton Bross, Biberttalstrasse24, Altenberg, near Nuremberg, Germany Filed Nov. 17, 1967, Ser. No.683,921 Claims priority, application Germany, Nov. 23, 1966, B 89,981Int. Cl. B431: 7/12 US. Cl. 401-112 26 Claims ABSTRACT OF THE DISCLOSUREIn a writing tool such as a ball-point pen with a writing insert whichis adapted to be moved within a casing so as to project therefrom or tobe fully retracted therein, an improved actuating mechanism in which theelement which locks the relatively movable parts together consists of arocker. For counteracting fatigue of the material of the rocker, theinvention provides an additional spring element the resilience of whichassists in bending the rocker back to its normal inactive position. Thisspring element preferably consists of the return spring which acts uponthe writing insert.

The present invention relates to a writing tool and especially to a.ball-point pen which comprises at least one lead, ink carrier orball-point refill (hereafter collectively referred to as lead) which isslidable in its axial direction within a tubular casing, and apressure-actuated mechanism for advancing and retracting the lead sothat its writing point projects or is withdrawn from the front openingof the casing and for arresting the lead in the advanced and retractedpositions. This mechanism comprises two main components which aremovable relative to each other in the axial direction of the casing andone of which is a pressure-applying element, for example, a pushbutton,which acts upon the lead and is advanced and retracted against or underthe action of a retracting spring, respectively, while the othercomponent is the tubular casing. One of these components, preferably thepressureapplying element, is provided and preferably integral with arockerlike member which may be bent resiliently from a normal positionin a radial direction relative to the longitudinal axis of the casingand, if the pressure-applying element is nonrotatably mounted in thecasing, also in a peripheral direction. This rocker carries a controlcam which, when the pressure-applying member is moved, cooperates withguide edges which are provided on the other component and is therebymoved to two arresting positions which are associated with the advancedand retracted positions of the lead and are located above or behind eachother, as seen in the longitudinal direction of the casing.

If such a mechanism is made of plastic as it is very often done today,there is the possibility that after frequent bending of the rocker itsmaterial will show signs of fatigue, especially if the rocker hasremained for a longer period in its bent position away from the normalposition. The reduction in the elasticity of the rocker due to fatiguemay seriously impair the proper function of the mechanism. It istherefore the principal object of the present invention to prevent theoccurrence of such a fatigue of the material as much as possible. Forattaining this object, the invention broadly consists in the provisionof a spring element which assists in bending the rocker back to at leastone of its normal positions.

According to one preferred embodiment of the invention this is attainedby designing the spring which moves the pressure-applying element to itsretracted position so as also to serve as a resilient element forbending the rocker back to its normal position. It is, however, also3,438,715 Patented Apr. 15, 1969 possible to employ a separate springelement between the foot of the rocker and the pushbutton which isadapted to take up substantially the tensions which are produced whenthe rocker is being bent and which forms the pivot joint for the rocker.Of course, these two functions may also be carried out by the sameelement.

While with a pushbutton which is rotatably mounted it will generallysufiice if the spring element supports the radial movement of the rockerin the direction toward its normal position, it is advisable when thepushbutton is nonrotatable to design the spring element so as also totend to counteract and reverse the peripheral deflection of the rocker.

According to the invention, the fatigue of the material is counteractedalso by making the guide edges which cooperate with the control cam andare preferably provided on the wall of the casing of a novel andadvantageous design. The invention is for this purpose based on theconcept that the guide edges should be designed so that, when the leadis in its advanced position, the rocker should be bent only veryslightly in the peripheral direction relative to the position in whichit is located in the retracted position. One of the features of theinvention for accomplishing this object consists in providing two guideedges which are located above each other, as seen with reference to thelongitudinal axis of the casing, and are inclined in the same directionand are provided at their rear end near the rear end of the casing withan arresting position for the control cam for holding it in theretracted position or in the advanced position of the lead. Thearresting position which is provided on the lower guide edge is offset,preferably for a distance less than the width of the cam, relative tothe arresting position on the upper guide edge in the direction towardthe end of the upper guide edge which is most remote from the rear endof the casing. Another feature of the invention for attaining theabove-mentioned object consists in providing at least one stop edgewhich extends in the longitudinal direction of the casing and preventsthe rocker when passing from the upper guide edge to the arrestingposition on the lower guide edge from pivoting beyond this position.Another feature of the invention consists in providing a releasing edgewhich is located underneath the lower guide edge and bends the cam whichis pressed against it so far back in a radial direction that it will bemove-d to a position outside of the range of action of the stop edgewhich extends in the longitudinal direction. A further feature forattaining the above-mentioned objects consists in providing a controlcam which extends substantially in a radial direction and has on itslower side a Worksurface which cooperates with the uppermost guide edgeand on its upper side a work surface which cooperates with the guideedge underneath thereof. The term cam as used herein in connection withthe invention is intended to mean any kind of radial projection.

For simplifying the manufacture and assembly of the writing toolaccording to the invention, it is another of its features to provide theguide edges on an extension of the casing which projects from the rearend thereof and is preferably integral therewith and only partlysurrounds the pressure-applying element, for example, the pushbutton,preferably to an extent less than one half of its peripheral surface.When designing the writing tool in this manner, the advantage isattained that the component of the mechanism on which the guide edgesare provided may be much more easily molded than when these edges areprovided on a peripherally closed part, for example, on the casing ofthe writing tool itself.

The features and advantages of the present invention will become moreclearly apparent from the following detailed description thereof whichis to be read with reference to the accompanying drawings, in whichFIGURE 1 shows a longitudinal section of the rear part of the casing ofthe writing tool with the operating mechanism therein;

FIGURE 2 shows a view similar to FIGURE 1 but taken from one lateralside thereof;

FIGURE 2a shows a modification of the embodiment depicted in FIGURE 2.

FIGURE 3 shows an enlarged side view, as seen from the right of FIGURE2, of the part of the casing in which the guide and releasing edges aswell as a part of the stop edges for the control cam are formed byapertures in the wall of the casing;

FIGURE 4 shows a cross section which is taken along the line IVIV ofFIGURE 3;

FIGURES 5 and 6 show two views similar to FIGURE 4, in which the controlcam is shown in two different operating positions;

FIGURES 7 and 9 show cross sections which are taken along the line VII-VII of FIGURE 3, in which the cam is shown in three other operatingpositions;

FIGURE 10 shows a view similar to FIGURE 3, in which the cam isillustrated in the same position as shown in FIGURE 8;

FIGURE 11 shows a view of the inside of part of the casing of a writingtool according to a modification of the invention in which the guideedges are provided by projections on the inner side of the casing;

FIGURE 12 shows a side view of a modification of the pushbutton which isprovided with a resilient member between the foot of the rocker and theactual pushbutton;

FIGURE 13 shows a side view of the pushbutton according to anothermodification of the invention;

FIGURE 14 shows a side view of the rear end of a writing tool accordingto another modification of the invention. in which the guide edges areprovided on an extension of the casing;

FIGURE 15 shows an enlarged side view similar to FIGURE 3 of a furthermodification of the invention;

FIGURE 16 shows a cross section which is taken along the line XVI-XVI ofFIGURE 15; while FIGURES 17 to 19 show enlarged side views of thecontrol cam according to FIGURES 1 and 2, as seen from different sidesthereof.

While in FIGURES l to 10 and 17 to 19 the individual parts of the firstembodiment of the invention are designated by numerals from 1 to 30,those parts of the five modifications of the invention as shown inFIGURES 11 to 16 which are either equal or functionally similar theretoare designated by the same numerals which, however, are distinguishedtherefrom by being increased by 100, 200, 300, 400, or 500,respectively.

The actuating or pressure-applying member 1 in the form of a pushbuttonis guided in the tubular shank or casing 2 so as to be slidable thereinin the axial direction. In the first embodiment of the invention asshown in FIGURES l to 11, this pushbutton 1 is prevented from turningwithin the casing 2 by having a substantially square cross section inaccordance with the shape of the casing 2. The lower end of thepushbutton 1 has eccentrically thereon an extension 4 which is connectedby an arm 6 to a rocker 5 which extends parallel to the axis of easing2. The parts 1, 4, 5, and 6 may be integral with each other and consistof a resiliently deformable molded piece of plastic so that the rocker 5may be resiliently bent or pivoted in the radial direction as indicatedby the arrow A in FIGURE 2 and also in the peripheral direction asindicated by the arrow B in FIG- URE 1. For bending the rocker 5 in theperipheral direction, the extension 4 serves as a flexible joint similarto a leaf spring.

Arm 6 of the mentioned plastic element has an obliquely inclined lowerside 6'. When a pressure is exerted upon this inclined side 6', a torquewith a lever arm 0 is exerted upon the rocker arm 5 which acts in theperipheral direction. In the embodiment as illustrated in FIG- URES 1and 2, this torque is produced when the rear end of the lead 7 ispressed by the return spring 8 against this inclined surface 6. InFIGURE 1, the rocker 5 is in its normal inactive position in which itsupper end carrying a cam 9 as subsequently described will be pressed bythe action of spring 8 against the wall of casing 2. When the pushbutton1 is being depressed and the rocker 5 is bent from its normal positionin the peripheral direction by a deformation of the extension 4, notonly the torque will occur which is caused by the mentioned lever actionbut also an additional torque which is produced by the resilience of thematerial. If the spring part, for example, the part 204 in FIGURE 1.2which is provided between the lower end of the rocker 5 and thepushbutton 1 is made of a suitable shape, the resilient force which isproduced by the deformation of the material may alone by sulficient toreturn the rocker to its normal position. Generally it is, however,advisable also to employ the force of spring 8 acting upon the lead 7 toaccomplish this purpose.

In the embodiment of the invention as shown in FIG- URES 1 and 2, therocker 5 is bent in the radial direction against the resilience of itsmaterial. This resilient tension may, however, be increased by thetension which is exerted by spring 8 if the surface 6 is suitablyinclined.

FIGURE 2a indicates a modification of the rocker arm in the form of atwo-armed lever, the upper arm of which is provided with the control camand the lower arm with the inclined surface 6 which engages upon therear end of the lead 7 so that a torque will be produced with a leverarm d which exerts an additional force upon the cam carrying arm whichtends to bend the latter back to its normal position.

The guide, releasing, and stop edges for the control cam 9 may bedesigned as illustrated in FIGURES 3 to 10, in which these edges areprovided on one side of the wall of a tubular shank or casing 2 whichhas a square cross section. For forming the guide and releasing edgeswhich are necessary for the operation of the device as subsequentlydescribed in greater detail, and for also partly forming the stop edgesfor the control cam, two parallel slots 10 and 11 are provided at acertain distance above each other in the wall of the casing 2 and areinclined in the same direction relative to the vertical axis of thecasing. The lower slot 11 is slightly shorter than the upper slot 10 sothat the end of the casing is offset relative to corresponding end ofslot 10 at a distance which is smaller than the width of the cam.

Control cam 9 is guided by the lower edge 12 of slot 10 and the upperedge 13 of slot 11. For passing the control cam 9 from slot 10 to slot11 or from the guide edge 12 to the guide edge 13, the inner side of thewall of the casing is provided with a groove 26 the lateral wall ofwhich forms a stop edge 27 for the cam which guides cam 9 up to the slot27 which prevents the rocker 5 from pivoting back during its movementfrom one slot to the other. Edge 28 which limits the slot 11 in thedownward direction has an additional guiding purpose, namely, to holdthe cam within the slot. At the other side of edge 27, as seen from thegroove 26, there is an inclined surface 16 (FIGURE 4) which ascends inthe direction toward the edge 27.

At the end of slots 10 and 11 or guide edges 12 and 13 which is closestto the rear end of the casing an arresting corner 14 or 15 is providedfor receiving the control cam in the retracted or advanced position ofthe lead 7, respectively. Each of these arresting corners is formed bythe upper corner of the respective slot. In FIGURE 3, the retractedarrested position of cam 9 is indicated in full lines and its advancedarrested position in dotted lines. Underneath the control cam when inits advanced arrested position, slot 11 is provided with a releasingedge 17 which is inclined in the opposite direction to the inclinationof guide edge 13 relative to the vertical axis of the casing. Inalignment with the arresting corner 14 and parallel to the axis of thecasing is a stop edge 30 which is formed by the inner side of therespective side wall portion of the casing.

Control cam 9 is provided on its lower side with a work surface 18 whichextends parallel to and overlaps the uppermost guide edge 12 and islocated substantially vertically to the plane of rocker 5. The upperside of control cam 9 is provided with an inclined surface 19 whichextends in the same direction as guide edge 13 and ascends within thecasing from the inside toward the outside and coopeartes with the guideedge 13. Cam 9 is further provided with an inclined work surface 20which extends from the inside toward the outside and is adapted to pressthe cam against the reversing edge 17.

Cam 9 is further provided with a stop surface 29 which cooperates withthe stop surfaces 27 and 30. In the embodiment of the invention as shownin FIGURES 1 to 4, the work surface 20 extends from a point within theupper part of the front side of the cam to a point within the lower part.of the rear side of the cam (see FIGURE 2).

The course of movement followed by the control cam during its operationis indicated in FIGURE 3 by a dotand-dash arrow line. When cam 9 is inthe arresting corner 14 (FIGURES 3 and 4) corresponding to the retractedposition of the lead 7, and the pushbutton 1 is then depressed, the worksurface 18 of the cam will slide along the guide edge 12 (FIGURE 5)until it reaches the end of groove 26 into which it will then enter(FIGURE 6). In the course of this movement of the control cam, rocker 5is bent from its normal position in the peripheral direction, The rockerwill remain thus deflected as long as the cam in passing from theuppermost guide edge 12 to the lower guide edge 13 slides within groove26 since the surface 29 of the control cam then engages laterally uponthe guide edge 27. When the cam enters the slot 11, rocker 5 can swingback so far under the action of the resilient resetting force asproduced during its previous deflection that it will abut against thestop edge 28. At this moment, the operator may stop pressing upon thepushbutton 1. Cam 9 will then slide along the edge 28, and its surface29 will abut against the outer edge 21 of slot 11. During the furtherretraction of the pushbutton, cam 9 will pass into the arresting corner(FIGURE 9).

If the pushbutton 1 is depressed in the forwardly shifted arrestingposition, the inclined work surface of the control cam will run againstthe releasing edge 17. The cam is thereby pushed back in the radialdirection (FIG- URES 8 and 10). This is due to the fact that the cam isprovided with surfaces which extend obliquely from the inside to theoutside and from above downwardly. It thus passes out of the range ofaction of the guide edge 21. Due to the remainder of the resetting forceacting upon it, the rocker arm 5 may thereafter swing back to its normalperipheral position. Surface 29 of the control cam then abuts againstthe edge (FIGURE 9). The movement to this position is assisted by thecourse of the inclined surface 16 on the inner side of the casing. Itmay be noted that in this position the rocker arm 5 will be bentresiliently slightly inwardly because its condition of rest correspondsto those positions in which the cam passes through the slots 10 and 11.When the pushbutton is released, cam 9 which is guided on the edge 30will shift in the opposite direction along a path extending parallel tothe axis until it again reaches the slot 10* into which it will thenengage under the action of the resilient tension of rocker arm 5. Cam 9will then again slide into the arresting corner 14 and will thus againbe in the retracted position.

It should further be pointed out that in the embodiment of the inventionas shown in FIGURES 1 to 10, the bottom of groove 26 and that part ofthe inclined surface 16 which is directly adjacent to the edge 30 liesubstantially within the same plane. Consequently, cam 9 can run alongthe guide edge 12 only when it is in a position (which also correspondsto the position of rest) which is slightly offset toward the outsiderelative to that position in which the cam cooperates with the bottom ofgroove 26. In order to move the cam to this position, the upper end ofthe rocker is provided with a slight curvature 5a, as indicated inFIGURE 4, which extends in the outward direction. When the pushbutton isbeing depressed, this part cooperates with the inclined surface 16 whichthen serves as a guide surface, whereby the rocker is bent inwardly andsubjected to a slight elastic deformation. The control cam can thenengage into groove 26 when the rocker 5 engages upon the edge which islocated at the point of transistion from the inclined surface 16 to thestop edge 27.

The rocker 5 is spaced from the pushbutton 1 at such a distance that thelatter when in the position as last described will form a stop so thatrocker 5 cannot carry out any radial movement of a sufficient amplitudeto cause an unintentional release of the control cam relative to theguide edge.

The embodiment of the invention as illustrated in FIG- URE 11 has theadvantage of being more easily molded since the different edges areprovided on projections 122', 122", and 123. The grove 124 extendingparallel to the axis between the projections 122' and 122" has noimportance insofar as the operation of the device is concerned but it isprovided for facilitating the molding operation. This groove 124 must,of course, have a smaller width than the cam 109. The reversing edge 117on the projection 123 is provided with a radially extending inclinationwhich is additionally inclined. in the direction of movement of the camand corresponds to work surface 20 on cam 109 of the embodiment aspreviously described. When the cam is pressed against the guide edge117, it will be pressed radially toward. the inside and thereby passagain out of the range of the arresting corner which corresponds to theforward arresting position. In addition it should be mentoined that theretracted position of the cam of this embodiment is fixed by specialmeans, for example, by an additional rocker (not shown).

FIGURE 12 shows a pushbutton which is axially slidable within the casingbut nonrotatable due to the provision of a projection 203 which engagesinto a groove in the inner side of the wall of the casing. The resilientelement 204 is provided in the form of a torsion rod which extendsparallel to the axis between the foot of the rocker 205 and thepushbutton and is integral with the latter. When the rocker 205 pivotsin the peripheral direction, the elastic tension which is therebyproduced is taken up by the torsion rod so that the material of therocker itself will not be stressed or even be releaved of stress.

In the embodiment of the invention as illustrated in FIGURE 13, thecontrol cam 309 and the inclined surface 306' against which the rear endof the lead 307 is pressed by spring 308 are provided on the same freeend of rocker 305. This arrangement assists in bending the rocker backto its normal position.

While in the embodiments of the invention as previously described theguide, releasing, and stop edges are provided on the wall of a fullyclosed tubular element, FIGURE 14 shows an embodiment in which theseedges are provided on an extension 425 of the rear end of the casing.The guide and releasing edges are in this case formed by slots 410, 411as in the embodiment according to FIGURE 3. Of course, it is alsopossible to provide these edges similarly as in the embodiment accordingto FIGURE 11 by projections which are molded on the side of extension ofthe casing facing the pushbutton.

FIGURES 15 and 16 show a further embodiment of the invention in whichthe releasing edge .517 is differently arranged relative to the forwardarresting position of the cam than in the embodiment according to FIGURE3. The reversing edge 517 is located within a line extending parallel tothe axis above the position in which cam is pivoted when leaving thearresting position on the lower guide edge. The inclined work surface520 of the cam which cooperates with the reversing edge 517 is thereforeinclined in the opposite direction to the inclination as in theembodiment according to FIGURE 3. The work surface 520 now ascends fromthe front side of the cam toward its rear side, as may be clearly seenin FIG- URE 16. This drawing also shows that the work surfaces 519, 518on the upper and lower sides of the cam and also the associated edges onthe wall of the casing are inclined so that these work surfaces willengage behind these edges. Thus, the upper work surface 519 isdownwardly inclined from its front side toward its rear side, while thelower work surface 518 is upwardly inclined from its front side towardits rear side. This has the result that, when the work surfaces of thecam press against the edges, a force component is produced which drawsthe cam into the effective range of the edges so that faulty operationswill be avoided.

When speaking in the previous description of the invention of the frontside of the cam, that side is meant which laterally projects from therocker more than the opposite rear side. This rear side of the camgenerally does not project but merges directly with the cam.

Although my invention has been illustrated and described with referenceto the preferred embodiments thereof, I wish to have it understood thatit is in no way limited to the details of such embodiments but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed my invention, what I claim 1. A writing toolhaving at least one lead slidable in the axial direction within atubular component and a pressure-actuated device for advancing andretracting the lead point through or from the front opening of thecasing of the writing tool, respectively, and for arresting the lead inthe advanced or retracted position, said device comprising two operatingmembers movable relative to each other in the axial direction of thecasing, one of said members being the pressure-applying element whichacts upon the lead and the advancing and retracting movements of whichoccur against or under the action of a spring, respectively, the otheroperating member being the tubular component, one of said operatingmembers, preferably the pressure-applying element, being provided withat least one rocker which may be bent from a normal position in a radialdirction and thereby produces a resilient resetting force in relation tothe longitudinal axis of the casing, and which, if the pressureapplyingelement is nonrotatably mounted, may also be bent in a peripheraldirection, said rocker carrying a control cam "which during the movementof the pressureapplying element cooperates with guide edges provided onthe other operating member and is thereby passed to arresting positionswhich are located above each other and are associated with the advancedand retracted positions of the lead, said writing tool further having aresilient element adapted to assist in bending the rocker back to atleast one of its two normal positions.

2. A writing tool as defined in claim 1, wherein the resilient elementis formed by the spring which acts upon the pressure-applying element.

3. A writing tool as defined in claim 2, wherein the lead is locatedbetween the spring and the pressure applying element against the lowerpart of which the upper end of the lead engages, said lower part formingan extension of the actual rocker extending in a direction transverse tothe axis of the casing and being connected to the pressure-applyingelement by a joint located outside of the pressure point of the leadlying within the line of force of the pressure, said extension of therocker forming a lever arm which is pivotable in the axial direction.

4. A writing tool as defined in claim 3, wherein the contact surface onthe rocker for engaging with the lead forms an inclined surface.

5. A writing tool as defined in claim 3, wherein the rocker forms atwoarmed lever adapted to be bent in a radial direction and/ or in aperipheral direction and having one arm carrying said control cam, whilethe other arm is provided with the contact surface for the lead.

6. A writing tool as defined in claim 1, wherein the resilient elementis formed by a flexible joint which is located between the foot of therocker and the pressureapplying element and is adapted to take up thetensions produced when the rocker is being bent.

7. A writing tool as defined in claim 6, wherein the resilient elementis integral with the pressure-applying element and with the rocker.

8. A writing tool as defined in claim 6, wherein the resilient elementforms a torsion rod extending parallel to the axis of the casing.

9. A writing tool as defined in claim 6, wherein the resilient elementforms a leaf spring.

10. A writing tool as defined in claim 4, wherein the control cam andthe inclined surface are provided on the same end of the rocker.

11. A writing tool as defined in claim 1, comprising two guide edgeslocated above each other in relation to the vertical longitudinal axisof the writing tool and being inclined in the same direction and eachhaving on its end closest to the rear end of the wrting tool anarresting position for the control cam in the retracted or advancedposition of the lead, respectively, the arresting position on the lowerguide edge being offset, preferably for a distance less the width of thecam, relative to the arresting position on the upper guide edge, as seenin the direction toward the end of the upper guide edge remote from therear end of the writing tool, said writing tool further comprising atleast one stop edge for preventing the rocker when passing from theupper guide edge to the arresting position on the lower guide edge frompivoting beyond said arresting position, a releasing edge locatedunderneath the rarresting position on the lower guide edge and adaptedto bend the cam when pressed against it so far back in a radialdirection that it will be moved to a position outside of the range ofthe lower [arresting position, :and a control cam having on its lowerside a work surface overlapping the uppermost guide edge underneath.

12. A writing tool as defined in claim 11, wherein a further stop edgeis provided along which the cam slides up to the upper arrestingposition subsequent to the action of the releasing edge.

13. A writing tool as defined in claim 11, wherein the work surfaces ofthe cam cooperating with the upper and lower guide edges are providedwith an inclination corresponding to the inclination of the guide edges.

14. A writing tool as defined in claim 11, wherein the releasing edge islocated within a line extending parallel to the axis of the toolunderneath the control cam when the latter is in its forward arrestingposition.

15. A writing tool as defined in claim 11, wherein the releasing edge islocated within a line extending parallel to the axis of the writing toolabove the position in which the cam is pivoted when leaving thearresting position on the lower guide edge.

16. A writing tool as defined in claim 11, wherein the rocker is in itsnormal position when the control cam is located at the arrestingposition associated with the retracted position of the lead.

17. A writing tool as defined in claim 14, wherein the releasing edgehas an inclination extending in the opposite direction to that of thelower guide edge as seen with reference to the vertical longitudinalaxis of the writing tool.

18. A writing tool as defined in claim 11, wherein the cam is providedwith a further inclined work surface by means of which the cam may bepressed against the releasing edge.

19. A Writing tool as defined in claim 11, wherein the releasing edge islocated within a line extending parallel to the axis of the toolunderneath the control cam when the latter is in its forward arrestingposition, wherein the cam is provided with a further inclined worksurface by means of which the cam may be pressed against the releasingedge, and wherein the inclined work surface of the cam descends from thefront side toward the rear side of the cam.

20. A writing tool as defined in claim 11, wherein the releasing edge islocated within a line extending parallel to the axis of the writing toolabove the position in which the cam is pivoted when leaving thearresting position on the lower guide edge, wherein the cam is providedwith a further inclined work surface by means of which the cam may bepressed against the releasing edge, and wherein the inclined worksurface of the cam ascends from the front side toward the rear side ofthe cam.

21. A writing tool as defined in claim 11, wherein the guide edgeprovided underneath the lower arresting position has an inclined buttingface for the cam on which the latter is bent back.

22. A writing tool as defined in claim 11, wherein the surface againstwhich the cam is pressed when passing from the lower guide edge to theupper guide edge has an inclination adapted to assist in pivoting therocker in the direction corresponding to the retracted arrestingposition.

23. A writing tool as defined in claim 1, wherein the guide and stopedges are provided on an extension of the rear end of the casing of thewriting tool which is preferably integral with the casing itself andonly surrounds a part of the pushbutton, preferably less than one halfof its peripheral surface.

24. A writing tool as defined in claim 11, wherein the work surface onthe upper side of the cam is downwardly inclined from the front sidetoward the rear side of the cam and the edges cooperating with this worksurface and provided on the other operating member are inclinedaccordingly and the work surface on the upper side of the cam engagesbehind these edges,

25. A writing tool as defined in claim 11, wherein the work surface onthe lower side of the cam is upwardly inclined from the front sidetoward the rear side of the cam and the edges on the other operatingmember cooperating with this work surface are inclined accordingly andthe work surface on the upper side of the cam engages behind theseedges.

26. A writing tool as defined in claim 1, wherein the upper end of therocker is curved slightly outwardly in the radial direction.

References Cited UNITED STATES PATENTS 3,179,087 4/1965 Kuhn et a].401--1l2 3,196,839 7/1965 Bertoglio et al 401112 LAWRENCE CHARLES,Primary Examiner.

